Reduce networking delays for a more responsive app

6:21 - Enable connection migration on URLSessionConfiguration for HTTP/3

let configuration = URLSessionConfiguration.default
configuration.multipathServiceType = .handover

6:29 - Enable connection migration on NWParameters for QUIC

let parameters = NWParameters.quic(alpn: ["myproto"])
parameters.multipathServiceType = .handover

7:08 - Opt-in to QUIC datagrams

// Only one datagram flow can be created per connection
let options = NWProtocolQUIC.Options()
options.isDatagram = true
options.maxDatagramFrameSize = 65535

8:12 - Network quality tool in MacOS

networkQuality -s -C https://myserver.example.com/config

10:59 - Recommended configuration for Apache Traffic Server

% cat /opt/ats/etc/trafficserver/records.config

# Set not-sent low-water mark trigger threshold to 128 kilobytes
CONFIG proxy.config.net.sock_notsent_lowat INT 131072

# Set Socket Options flag to the sum of the options we want
# TCP_NODELAY(1) + TCP_FASTOPEN(8) + TCP_NOTSENT_LOWAT(64) = 73
CONFIG proxy.config.net.sock_option_flag_in INT 73

...

# Enable Dynamic TLS record sizes
CONFIG proxy.config.ssl.max_record_size INT -1

...

# Reduce low-water mark and buffer block size for HTTP/2
CONFIG proxy.config.http2.default_buffer_water_mark INT  32768
CONFIG proxy.config.http2.write_buffer_block_size   INT 262144

12:52 - Responsiveness tests

https://www.waveform.com/tools/bufferbloat
https://github.com/network-quality/goresponsiveness
https://www.speedtest.net/

17:12 - Enable L4S for QUIC on Mac

defaults write -g network_enable_l4s -bool true